/Engine/Plugins/Experimental/MeshModelingToolsetExp/Source/MeshModelingToolsEditorOnlyExp/Public/SkeletalMesh/SkinWeightsPaintTool.h
Store a sparse set of modifications to a set of vertex weights for a SET of bones with support for merging edits. these are used for transaction history undo/redo.
struct FMultiBoneWeightEdits
TMap<BoneIndex...
PerBoneWeightEdits
Map of bone indices to weight edits made to that bone